CR120F?

Ratranger · Nov 28, 2020

So this all started because I have a 79 XL75, that I put a built xr100 motor in. 120 big bore, cam, ported, 24mm flat slide, tiny flywheel. It's a blast because it's so overpowered, but the suspension and ground clearance are terrible.

Enter the $75 CR80R. Doing a little reading on forums and plenty of people have swapped the XR motor into a CR. Gives you a stronger frame, better suspension, and a motor that is great for a play bike. It's a bit involved, like cut out the entire engine cradle. But I'm making progress.

ThatXS650Guy · Nov 28, 2020

Nice. I have a what I call a CXR220 which is a stroked XR200 motor grafted into a CR125 chassis. We built two of them to compete in the White Brothers 4 stroke Nationals in the early '90s. They were cheater bikes because we could compete in the 200 class against stock XR200s but we could do the jumps.
Good times....

Ratranger · Nov 28, 2020

Nice, the biggest downside to the XRs are the outdated suspension and weak frames. I've seen CR80s with an XR200 swapped in. But everything I've read says the motor is too heavy and messes with the handling, where the 100 motor makes a sweet handling trail bike.

ThatXS650Guy · Nov 29, 2020

Ratranger said:
Nice, the biggest downside to the XRs are the outdated suspension and weak frames. I've seen CR80s with an XR200 swapped in. But everything I've read says the motor is too heavy and messes with the handling, where the 100 motor makes a sweet handling trail bike.

You could be right. The XR200 is a fun little trailbike but not much of a motocrosser. The stroke kit turns that happy little engine into snorting beast. I've had people mistake it for a 500 from the sound and the way it climbed hills. I'll have to snap a pic. It's been retired to the basement since 1999 with a broken kickstarter gear. One of these days when I run out of projects.

Ratranger · Nov 30, 2020

I had an xr200 with a 215 piston in it. It was plenty of power for a trail bike. I've ridden newer ttr230s, dr200s, and after the XR they just feel weak. The XR would easily loft the front wheel in 1-3, where the ttr struggled even in 1st. The new crf250f feels the most like the xr did, never got to try a crf230.

Ratranger · Dec 2, 2020

A little more progress

Ratranger · Dec 4, 2020

Engine back in, ready to makethe front mount.

And if you have a portaband the stand from swag offroad is amazingly handy.

Ratranger · Dec 5, 2020

Getting closer.

Ratranger · Dec 7, 2020

While I wait on suspension parts I modified my parts washer. It's a standard 20 gallon from HF. The original pump died(didn't like solvent). So I started by drilling a 2" hole in the bottom and installed a drain. The drain runs into 2 home depot buckets, the inner bucket has a bunch of holes drilled in it. This lets the gunk settle out where it won't be circulated by the pump. The pump was replaced with a little giant solvent rated pump, which is down in the bucket. The added bonus is parts don't get lost in the solvent anymore and I have more room to work.

ThatXS650Guy · Dec 7, 2020

Interesting modification. I bought one of those back in the mid -90's and the original pump is still going strong. I use kerosene in mine.
I took a pic of my CXR220. Not a good one as I was too lazy to move enough of the other crap out of the way. It was retired after the kick starter gear broke (again) and when I brought home a brand new 2001 YZF426.

Ratranger · Dec 7, 2020

They might have cheaped out on the pumps over the years. The original pump lasted a couple weeks with the psc1000 they sell at tractor supply.

Nice, I bet that is a fun bike. It seems the 200 and below XRs have weak kick gears. I've read about a bunch of them failing.

Ratranger · Dec 9, 2020

Forks and shock are rebuilt. I'll deal with valving and spring upgrades once it's running and test ridden. Looks like the stiffest springs for a crf150r match what is recommended on the forks for a good bit less than aftermarket. The BBR shock spring is right there as well and cheaper than others. But then I'll have to decide if I want to modify the stock shim stacks or get gold valves.

Ratranger · Dec 18, 2020

Now the suspension has all new bearings. And since it was taking forever for the bearings to show up the partswasher now has a filter.

Ratranger · Jan 8, 2021

Well it's been a little, but there are updates. Subframe was replaced with a NOS unit, plastics are here, new rims are laced to the hubs, and waiting on a 24mm dellorto pumper from germany.

ThatXS650Guy · Jan 8, 2021

Is that tank going to work? We ended up going with one from an ATK. 4.0 gallons provides a lot of range.

Ratranger · Jan 8, 2021

It should be fine. It's 1.3 gallons, that should get it farther than the 1.9 gallons my ktm 250 holds. If I entered an endurance race I'd think about a bigger tank.

Ratranger · Jan 17, 2021

A few updates, still waiting on the dellorto, and muffler. But got the header started, new bearings and tires on the new rims, so it's slowly getting there.

Ratranger · Jan 22, 2021

It looks closer to being a bike. Took it off the bench and threw the wheels and plastics on.
Still to be done list:
Muffler, ordered but not here.
Carb, been in transit a while
Oil cooler, have it, know where it's going.
Brakes, rebuild rear, waiting on bracket for 2 piston in the front
Coil and CDI, just gotta make mounts
Upper triple? Might make a billet one to move the bars forward.

Ratranger · Feb 2, 2021

Working on a bolt on kickstand. Started with foam board, and now transfering it over to steel.

Ratranger · Feb 8, 2021

Lots of work done, new brake lines, rebuilt rear master and caliper, bled brakes, protaper bars, 6.2kg rear spring, .36kg front springs, and kickstand is almost finished.

CR120F?

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XS650 Junkie

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XS650 Junkie

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XS650 Junkie

XS650 Junkie

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XS650 Junkie

XS650 Junkie

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